So at the start of the 3 resistors it is 330V and then at the end its 9v. Once it has naturally drained over night, i'm going to measure the resistance of that SMT resistor tomorrow. I have checked the resistance of the 3 18k resistors and they're all working at their expected resistance of 18k each. If they are broken in any way they wouldn't read 18k, right? They wouldn't malfunction and drop the incorrect voltage or anything while being 18k on the multi-meter, its safe to assume they're working fine, or would you want me to measure the voltage at each stage of that string of resistors in series?

 

Normally the voltage across any dropping resistors would be full DC voltage, minus 5v.
Did you ever get a draft schematic completed?
Max.

 

I didn't finish it, I have kept what i did and will attempt to complete tonight/tomorrow if you're interested in the full circuitry.

 

Would appreciate seeing the schematic if possible.
Max.

 

Okay, if you could give me a couple of days then i will report back with a schematic. What is the termanology for this resistor and diode in parallel to perform the voltage drop, what is its complete name? I would like to do some research on the subject.

 

Not sure how they are doing it the simplest way with minimum components and a common way is with the series resistor, zener to GND with a cap in parallel.
It would simply be zener derived supply regulation.
When dealing with HV sources it is usually only practical for low current circuits to avoid very large series resistors.
Max.

 

Okay, cool, thank you Max. I really appreciate the knowledge you're feeding to me. Learning a lot from this!

 

I've hit a sticking point in discovering parts...

In the image below i have circled the device that i have been searching and trying to work out for a while what it is now. I originally thought it would be a diode of some sort, maybe even that zener + resistor combo you speak of. But there is no marking what so ever, no polarity line, no figures, nothing. I have used a multi meter in diode mode and it returns "911" on the screen one way and then overloads the measurement the other way. Could this possibly be a bad diode? So i started to search around and then decided to take a measurement of the resistance of this device, it is 6.8K Ohms in both directions. I would expect a bad diode to be reading a higher resistance or a 0. So then i started to probe further to discover that one side is actually connected to GND. So, i'm now thinking that it could be a unmarked capacitor... However, when reading the resistance across a capacitor is it not supposed to read the resistance and then jump to a open line on the multi meter? I'm pretty sure that it is not a resistor as a bad resistor shows a high resistance or 0, and it is stable when read, not slowly climbing. This climbing characteristic is making me think it is a capacitor, but the image that i'm using off of eBay for the legend does not appear to show this as "C" legend letter... The image is really out of focus and therefor i can not read the label for this component. I have drawn on the copper traces in yellow so you can see the connections.

 

Did you use the resistance range of a DMM to test, as these generally do not have the forward bias current capability to identify and measure a SS device, unless it is shorted, a diode range should show the different conduction direction on a semi device.
I am wondering if those Semi cond devices that show no label has it under the device.?
Max.

 

I did use a digital MM indeed.

The label is on the board but due to wear and tear its been worn off and i can't find a detailed enough image to attempt to find the label.

 

Do you have a diode check range?
Max.

 

Do you have a diode check range?
Max.

If by diode check range you mean do i have diode mode on my multi meter then yes, however I can't set the range though. Its just like a continuity test mode.

 

I've been working my way through making a digital copy of the schematic that i have created and i came to one of the transistors, one that i have replaced. I have noticed that the label for this is U2, which would imply that it is not a transistor. I replaced it because i tested it for shorts and it came back as if it was bad, if it was a transistor. So i looked around for the markings and ordered what i thought was a replica. However, the label is now making me feel that it wasn't initially a transistor and i have replaced and thrown the old part away. I fear this was not a transistor and now i'm just screwed as i have no idea what is was.....

 

Was the center pin on that device grounded or connected to ground with a low (<200 Ω) resistor?
John

 

Pin 3, if its a npn transistor is connected to ground directly. So this would mean the collector is GND

 

Please post the partial schematic you have developed. It is unusual to connect the collector of an NPN transistor to ground (i.e., a supply voltage below that of the emitter).

John

 

This should be the finished schematic. Like you said, it is very unusual to place a NPN Transistor in this config. I'm not sure if i have replaced it with a NPN Transistor when it should be something else.

I have added the device in that i'm not too sure on as you can see, i have symbolized this with a box and some question marks. I'm thinking it is a diode tbh, do they do diodes that small that they don't mark them?

 

Please post the partial schematic you have developed. It is unusual to connect the collector of an NPN transistor to ground (i.e., a supply voltage below that of the emitter).

John

U2 is the device in question regarding the possible misplacement of a part.

 

The diagram of U2 I agree does look odd with the collector at GND?
The ?????? device appears to be some kind of low voltage regulation component.
Max.

 

I'm finding it really weird and finding myself assuming that i have put the wrong part in there.

I'm not sure how the mystery device could be a voltage regulating device when one side is GND and the other is connected to that low voltage line. Surely to be a low voltage regulating device it would need an input, output and GND?